John geeaves hawkins



UNITED STATES PATENT OFFICE.

JOHN GREAVES HAWKINS, OF WIGAN, COUNTY OF LANCASTER, ENGLAND.

PROCESS OF PURIFYING GOAL-GAS.

SPECIFICATION forming part of Letters Patent No. 328,309, dated October13, 1885.

Application filed August 3, [885. Serial No. 173,438. (No specimens.)Patented in England June 29, 1881, No. 2,849.

To all whom it may concern:

Be it known that 1, JOHN GREAVES HA KINS, of Wigan, in the county ofLancaster, England, have invented new and useful Improvements inProcesses of Purifying Coal-Gas, (for which I have obtained a Patent inGreat Britain, No. 2, 849, bearing date June 29, 1881,) of which thefollowing is a specification.

In the ordinary method of purifying coalgas by means of oxide of iron,it is well known that the oxide has at frequent intervals to be removedfrom the purifiers and exposed to the air, so as to revivify, it as itis called, or render it capable of acting again in the purifiers, andthis entails great labor and expense, together with loss of gas, andsometimes considerable nuisance. To reduce these results,

atmospheric air has at times been drawn or forced in along with the gasthrough the purifying material, so as to effect the revivification inthe purifiers; but atmospheric air alone so drawn in dilutes the gas,lowers its illuminating-power, and becomes dangerous.

The object of this invention is to produce a continuous revivificationof the oxide in the purifiers, and so reduce the trouble and cost ofpurification without injuriously affecting the quality of the gas.

The invention consists in causing a carefullyregulated quantity ofatmospheric air to enter an apparatus, chamber, or vessel wherein thetar or the light portions thereof resulting from the carbonization ofcoal is subjected to a temperature of about 170 Fahrenheit, so as toeliminate the volatile hydrocarbons. The air thus introduced may betaken in at the ordinary atmospheric temperature; or it may be heated toany degree below which the heavy hydrocarbons from the tar would bevolatilized. The air in passing through the apparatus becomes chargedwith some of the lighter hydrocarbons, and this mixture is deliveredinto the main conveying the gas from the retorts immediately after theoutlet of the scrubbers, so as to insure the carbureted air mixinguniformly with the gas before entering the oxide-purifiers.

It is to be understood that to carry out this arrangement it isnecessary to force the air into the gas by means of a suitablemachine-such as an exhauster, for instance-by which the quantity of airmay be also regulated at will. The minimum quantity of air to beintroduced is that absolutely required to revivify the oxide of iron. Ifind that in order that the process may be carried out in such a manneras to prevent the presence of free oxygen in the purified gas, theremust be a sufficiently large area of oxide-purifiers to allow the gas topass slowly through them,and so insure the revivification of the oxidegoing on gradually and continuously, as where this is not the case therevivification is not complete,and the oxygen of the air is notcompletely removed, but goes on with the gas and diminishes itsilluminating-power; but, when the process is carried on as I havedescribed the oxygen combines with the iron, the revivification goes oncontinuously, and the heat never rises in the pnrifiers suificiently tofuse or partly fuse the sulphur. There is therefore no clogging of thematerial in the purifiers and consequent increase of pressure, and theprocess of revivification may be continued without the removal of theoxide from the purifiers until the oxide is practically saturated withsulphur.

When lime purifiers are used to eliminate sulphur compounds other thansulphureted hydrogen,I prefer to introduce the carbureted airimmediately after the outlet of such lime purifiers and before theoxide-of-iron purifiers; and to insurethe uniform mixing of thecarbureted air with the gas before entering the oxide-purifiers it isadvisable to have a considerable length of main between the two sets ofpurifiers; or the gas may be caused to flow through a suitable vessel inwhich the mixture may take place.

The drawing or forcing of atmospheric air through oxide of iron while inthe purifiers in order to revivify it is old; but the drawing or forcingof carbureted air either at the ordinary atmospheric temperature orartificially heated for this purpose is new, and is such an improvementthat the gas is increased in bulk, the illuminating-power is notdiminished, the trouble and expense of the frequent removal of the oxidefrom the purifiers are reduced, and the danger arising from the oxidebecoming unduly heated is reduced to a minimum.

of the tar are volatiiized, substantially as described.

In testimony whereof I havehereunto signed 15 my name in the presence oftwo subscribing witnesses.

JOHN GREAVES HAWKINS.

Vitnesses:

JOHN S. HoPWooD,

Solicitor, ig an, Lcmcashire, O. RUDDIoK,

Clerk to the said J 07m 8. Hopwood.

